Public telephone network

ABSTRACT

A public telephone network having a subscriber line for which the additional service feature of call forwarding to a predetermined destination call number is provided, the call forwarding being designed for the purpose of forwarding a Message Waiting Indication and/or an E-mail Waiting Indication.

BACKGROUND OF THE INVENTION

Despite the rapid development of mobile radio networks and the Internet,the line-connected public telephone network (landline network) is still,by far, the most important professional and private source ofcommunication in industrialized countries. In Germany, the publictelephone network has almost 50 million subscriber lines connected toapproximately 1800 local exchanges and approximately 600 trunkexchanges. With the introduction of the ISDN (Integrated ServicesDigital Network) on the basis of the digital switching technology of thepublic telephone network, relevant additional services are provided forowners of ISDN lines. These additional services offered attracted morethan 3 million customers for ISDN lines by as early as 1997, and thisnumber continues to increase at a great rate.

The services offered by the (digital) public telephone network need tostake a claim on the market in the face of those offered by the mobileradio networks and the Internet, however, whereby the services offeredneed to be constantly extended. The providers of the public mobile radionetworks are naturally subject to the same compulsion.

Certainly one of the most important services for the subscribers is callforwarding or redirection, which for years has been part of the servicesoffered by the landline network and also by the mobile radio networksand, since the setup of suitable interfaces, has also become possiblebetween these networks.

Another important service which is of central significance for themobile radio networks, but is also becoming increasingly relevant to thesubscribers on the landline network, is the option of storing voice ortext messages within the network in a so-called mailbox or telebox. Partof this service is notification of the subscriber about a voice or textmessage which has been received via a so-called Message WaitingIndication (MWI). The progressive linking of data networks, inparticular of the Internet, to the public telephone networks results inthe notification of a subscriber about e-mails which he/she has receivedvia a so-called E-mail Waiting Indication (EWI) also gaining increasingpractical significance.

The present invention is, therefore, directed toward developing thepublic telephone network such that the user's utility value associatedwith voice and text storage in the network and also with services inconnection with the transmission of e-mails is increased further.

SUMMARY OF THE INVENTION

The present invention encompasses the fundamental concept of increasingthe practical utility value of the service features of Message WaitingIndication and E-mail Waiting Indication by virtue of these servicefeatures reaching the user not only on the line on which the relevantvoice or text message or e-mail has been received, but also at thelocation in which he/she is currently situated. It also encompasses theconcept of developing the service of call forwarding to this end suchthat it also permits forwarding of an MWI or EWI.

In preferred embodiments of this invention, interfaces are producedbetween landline networks and mobile radio networks such that theproposed forwarding is possible in both directions; landlinenetwork/mobile radio network and mobile radio network/landline networkand also between the mobile radio networks.

One provision within the scope of the present invention is that theexchanges or service switching points in the telephone network containparts for checking the presence of call forwarding on a subscriber lineassociated with them in response to the reception of an MWI and/or EWIon this subscriber line. They also contain parts for linking the MWI orEWI to the destination call number which was set within the context ofthe call forwarding, as well as parts for forwarding the MWI or EWI tothe exchange responsible for the destination call number or to thecompetent service switching point. The use of these parts provides thetelephone customer with the same service, in terms of the signaling ofan MWI or EWI, on a call forwarding line as on his/her standard line,which distinctly increases the attractiveness of the network's dedicatedstorage capabilities and, hence, the attractiveness of the networkoverall.

To prevent a forwarded MWI or EWI from being rejected by the new line'sassociated list of those mail servers which are authorized to transmitan indication to this line, the forwarded MWI/EWI needs to be providedwith an additional flag identifying it as forwarded information. Forparticular systems, the “Time” field of the report is suitable for thispurpose. The flag needs to be set by the exchange or the serviceswitching point for the call forwarding destination line.

In another preferred embodiment of the present invention, signalingparts are provided for acknowledging that the MWI/EWI has beenforwarded, or that the forwarding has been unsuccessful or has involvedan error, to the mailbox or the originator. In the first case, if anerror occurs, it is possible to make a fresh attempt at forwarding; inthe latter case, setup of the proposed novel service feature is linkedto the additional advantage that each subscriber can, by reason of this,be certain that the other party has actually become aware of the arrivalof a message which has been sent from the subscriber to a mailbox in thetelephone network. There would, accordingly, be exceptions only in thecase of an error, notification of which is explicitly sent to theoriginator.

In a similar way as in the case of call forwarding from one network lineto another, the scope of the present invention is also intended to coverthe forwarding of an MWI/EWI from one extension to another in a privatebranch exchange. This naturally requires that the private branchexchange be appropriately designed as such.

Additional features and advantages of the present invention aredescribed in, and will be apparent from, the following DetailedDescription of the Invention and the Figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a schematic illustration to explain a first exemplaryembodiment of the present invention.

FIG. 2 shows a schematic illustration to explain a second exemplaryembodiment of the present invention.

FIG. 3 shows a schematic illustration to explain a third exemplaryembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic illustration of how display of a Message WaitingIndication MWI for a voice message M which has been transmitted via theISDN network ISDN is redirected to a predetermined subscriber line.

A subscriber terminal A directs a call via the associated networktermination unit NT(A) and the exchange TVSt(A) associated with theA-subscriber to a B-subscriber, specifically to the call number for thelatter's terminal B1, which is connected to the competent exchangeTVSt(B1) via the network termination unit NT(B1). If there is no answer,the B-subscriber has activated the T-box in the ISDN network to record avoice message, and in so doing has at the same time specified that theMessage Waiting Indication MWI transmitted when the voice message isstored be forwarded (via an appropriate exchange TVSt(B2) and theassociated network termination unit NT(B2)) to a second terminal B2associated with him/her; for example, his/her private line. The“redirection” of the voice message M from the A-subscriber to the T-boxis identified by a dash-dot line in FIG. 1, and the transmission of theMWI to the terminal B2 is identified by a dashed line. Hatching of thedisplay (not given a specific designation) on the terminal B2 identifiesthe fact that the MWI normally appears there after the message M hasbeen received in the T-box.

It is now assumed that the B-subscriber has set, on his/her privateterminal B2, call forwarding to another private terminal B3 (whichnaturally again passes via a competent exchange TVSt(B3) and theappropriate network termination unit NT(B3)). There, a flag is set whichidentifies it as a forwarded Message Waiting Indication MWI/CFW. Theincoming MWI is then redirected to the exchange TVSt(B3) by the callforwarding. Although the call number for the terminal B2 is notcontained in the screening list of those mail servers which areauthorized to send an indication to the terminal B3, the indication isdetected as a forwarded indication on account of the flag which is set,and can pass to the terminal B3. It then appears on the display on theterminal B3, which is identified by a bold border and hatching in thedisplay area. This path of the MWI/CFW is identified by adash-double-dot line.

After the Message Waiting Indication has been successfully transmitted,the exchange TVSt(B3) transmits appropriate signaling to theA-subscriber, which signaling is symbolized by a double-dash-dot line inFIG. 1. (In the event of an error in the forwarding of the MWI, an errorsignal would accordingly be transmitted by the competent exchangeTVSt(B2) or TVSt(B3)). In this context, it may be pointed out that theanchoring of the acknowledgment function in the ETSI protocol willmerely provide signaling to the mailbox. The latter fundamentallyrepresents a private network, whereby the further handling of themessage is not covered by the standardization for the public network inthat case. The forwarding of the acknowledgment to the callingsubscriber which is assumed in this case is therefore only one of anumber of options. The simplest option is to ignore the acknowledgmentto the mailbox completely, which may result in an MWI or EWI with amisleading content, however. An option which is preferred over thisinvolves the error message in the mailbox being processed internally;for example, by correcting the total number of forwarded Message WaitingIndications or E-mail Waiting Indications to be reported. Finally,provision also may be made for the control parts for the mailbox toinitiate repeated transmission of the MWI/CFW or EWI/CFW so that theaddressee is still notified in spite of an error which has occurredfirst.

FIG. 2 shows, as a further example of the implementation of the presentinvention, an E-mail Waiting Indication (EWI) being handled within thecontext of call forwarding. An A-subscriber sends an e-mail to aB-subscriber via his/her personal computer PC(A), the associated networktermination unit NT(A) and the associated exchange TVSt(A) and also anetwork interface INT1 between the telephone network ISDN and theInternet. To this end, the A-subscriber logs onto his/her mail serverand sends an e-mail from the latter to a network address for anotherparty, the network address again being implemented by a mail server. Ifthe other party is logged onto his/her server, he/she has access tohis/her mailbox and receives the e-mail displayed on his/her screen. Sothat he/she does not need to be logged on constantly in order to be ableto receive e-mails reliably, his/her mail server can send him/her anE-mail Waiting Indication to his/her terminal via the public network. Itmay now be assumed that the B-subscriber has not turned on his/herpersonal computer PC(B1) in his/her absence and, besides, has setunconditional call forwarding (Call Forwarding Unconditional) CFW onhis/her terminal. According to the present invention, the associatedexchange TVSt(B1) is designed such that the call forwarding CFW whichhas been set also detects an incoming E-mail Waiting Indication EWI.

The E-mail Waiting Indication EWI signaling the storage operation in hisInternet mailbox for the B-subscriber is forwarded by the exchangeTVSt(B1) to the call forwarding destination call number prescribed bythe B-subscriber. In the case assumed, this is the call number for amobile telephone B2 connected to a public mobile radio network GSM. Theredirected E-mail Waiting Indication EWI/CFW passes as identified inFIG. 2 (in a similar way to in FIG. 1) by a double-dot-dash line, via aninterface INT2 between the landline network ISDN and the mobile radionetwork GSM, the competent mobile switching center MSC(B2) and the basestation BS(B2) associated with the location of the mobile telephone B2to the mobile telephone B2, where it is displayed on the latter'sdisplay. This is identified in FIG. 2 by hatching and a bold border forthe display area.

In a similar manner as in the first embodiment described above, a flagis added to the forwarded indication EWI/CFW in the exchange associatedwith the redirected line, that is to say in this case the exchangeTVSt(B1), the flag identifying the indication as a forwarded indicationand preventing any rejection by the screening list of authorizedoriginators for the mobile telephone B2. Likewise, in a similar manneras in the embodiment described above, if the EWI/CFW is successfullyforwarded to the originating A-subscriber, a type of acknowledgmentsignal SIG/CFW is transmitted which triggers appropriate display(symbolized in FIG. 2 as a vertically hatched area on the screen on thepersonal computer) on the A-subscriber's terminal PC(A). (In theinterests of clarity, the “alternative route” via the mailbox is notshown in FIG. 2).

In both embodiments, the B-subscriber informed about the arrival of avoice message or e-mail by the forwarded Message Waiting IndicationMWI/CFW or E-mail Waiting Indication EWI/CFW may, in a manner which isknown per se and is, therefore, not explained in more detail here,retrieve the voice message stored in the T-box or the e-mail stored onthe appropriate Internet server MSe immediately. The proposed solution,thus, provides him/her with the same options, in terms of messagesstored in the network, on a forwarding line as on a standard line.

The technical network implementation is described in ETSI documents ETS300 745 and ETS 300 754 and relates to the ISDN signaling for theterminal in the D-channel protocol (layer 3 FACILITY reporting) and tothe network signaling (TCAP) between the exchanges. In this respect,this signaling has been defined and need only be complemented by theflag in order to identify the forwarding of the MWI/EWI. The signalingshould be based generally on the existing standard and should onlyadditionally take into account the call forwarding as an interworkingcase.

As a third exemplary embodiment of the present invention, FIG. 3 shows aconfiguration involving storage of a voice message in the T-box of anISDN network, the configuration being similar to the arrangement shownin FIG. 1 to a certain degree. In the present case, it is assumed thatan A-subscriber transmits a message to a B-subscriber associated with amobile telephone A which is connected to a terminal B1 associated withthe B-subscriber via the competent base station BS(A), the appropriatemobile switching center MSC(A) in the mobile radio network GSM, aninterface (an access mobile exchange) INT between the mobile radionetwork GSM and a landline network ISDN, via the landline networkitself, an exchange TVSt(B1) and a network termination unit NT(B1).

Again, it is assumed that the B-subscriber has set, on his/her terminalB1, for example in his/her office, a voice memory function implementedvia the landline network ISDN (i.e., via the voice memory server T-boxtherein). As in the embodiment shown in FIG. 1, when the call from theA-subscriber arrives, the voice memory function is, therefore, activatedand a message transmitted by the A-subscriber is stored in the T-box. Itis also assumed that, when setting the voice memory mode, theB-subscriber has prescribed that a Message Waiting Indication MWI besent to a second line B2; for example, his/her private line.

This line is produced via a second exchange TVSt(B2) in the form of aprivate branch exchange TK(B2). The private branch exchange TK(B2) isprimarily programmed such that the Message Waiting Indication MWIappears on the display on a first connected terminal B2 a, which is inthe B-subscriber's study at home, for example. However, seeing the goodweather, the B-subscriber has decided to leave his/her study in order tostart working in the garden, and he/she takes a cordless telephone B2 bwith him/her as another terminal connected to the private branchexchange TK(B2). To this end, he/she has set unconditional callforwarding to his/her cordless telephone B2 b internally in his/herprivate branch exchange, which unconditional call forwarding, inaccordance with one development of the inventive concept, also includesredirection of an incoming Message Waiting Indication in the form of aredirected Message Waiting Indication MWI/CFW to the cordless telephoneB2 b. In this context, it is not necessary to set a specific flag, sinceno screening list of authorized originators is implemented in theprivate branch exchange. In the example shown, it is also assumed thatsignaling of the (internal) call forwarding back to the A-subscriber isnot provided.

SIEMENS (EWSD—digital electronic switching system) has also implementedMWI for analog subscriber lines. Since analog subscribers currentlystill make up the great majority in the network, they should also beable to forward the MWI/EWI. For this reason, the proposed feature isnot limited to specific signaling, such as ISDN or GSM, but rather canbe used generally for a public telephone network (PSTN).

Although the present invention has been described with reference tospecific embodiments, those of skill in the art will recognize thatchanges may be made thereto without departing from the spirit and scopeof the invention as set forth in the hereafter appended claims.

What is claimed is:
 1. A public telephone network having a subscriberline for which an additional service feature of call forwarding to apredetermined destination call number is provided, the call forwardingbeing designed for forwarding an indication, the indication being atleast one of a message waiting indication and an e-mail waitingindication, the public telephone network including at least one ofexchanges and service switching points comprising: parts for checking apresence of call forwarding on an associated subscriber line in responseto a reception of an indication on the subscriber line; parts forlinking the indication to the call forwarding destination call number;parts for forwarding the indication to at least one of the exchangeresponsible for the destination call number and the competent serviceswitching point; and parts for setting a call forwarding flag for theindication arriving via call forwarding for preventing rejection of theindication on a line of the destination call number.
 2. A publictelephone network as claimed in claim 1, wherein the public telephonenetwork is a land lying network provided with an interface to a mobileradio network, the interface being designed for forwarding theindication into the mobile radio network.
 3. A public telephone networkas claimed in claim 1, wherein the public telephone network is a mobileradio network provided with an interface to one of a land lying networkand another mobile radio network, the interface being designed forforwarding the indication into, respectively, the land lying network andthe mobile radio network.
 4. A public telephone network as claimed inclaim 1, further comprising signaling parts for acknowledging theforwarding of the indication to a mailbox.
 5. A public telephone networkas claimed in claim 4, wherein the signaling parts report an error whenforwarding the indication to the mailbox.